Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and methylisothiazolinone (MI) are tested to detect contact allergy to these isothiazolinones.
To study if an aqueous patch test preparation with MCI and MI in a mix of 0.015% and 0.2%, respectively, detects more contact allergies than the commonly used preparations of MCI/MI in 0.02% aq. and MI in 0.2% aq.
1555 dermatitis patients in 5 Swedish dermatology departments were consecutively tested with MCI/MI 0.215% aq., MCI/MI 0.02% aq. and MI 0.2% aq.
The share of contact allergy to MCI/MI 0.215% aq., MCI/MI 0.02% aq., and MI 0.2% aq. varied in the test centers between 7.9-25.9%, 3.2-10.3%, and 5.8-12.3%, respectively. MCI/MI 0.215% aq. detected significantly more patch-test positive individuals than both MCI/MI 0.02% aq. (P<.001) and MI 0.2% aq. (P<.001) as well as either one of MCI/MI and MI (P<.001). In the patients only reacting to MCI/MI 0.215% aq., 57.7% were recorded as having a dermatitis that was explained or aggravated by exposure to either MCI/MI or MI.
The results speak in favour of replacing the preparations MCI/MI 0.02% aq. and MI 0.2% aq. with MCI/MI 0.215% aq. as the screening substance in the Swedish baseline series, which has been implemented 2020. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.